1. Field of the Invention
The present invention relates to a shutter equipment for opening and closing such openings as building entrances and windows and particularly to an improvement of a slat opening/closing drive mechanism in a shutter equipment for opening and closing a plurality of slats which constitute a shutter.
2. Description of the Prior Art
The conventional shutter equipment of this type is composed of vertical guide rails disposed on both sides of an opening for opening and closing a shutter, with a slat stowing box being provided on top of the vertical guide rails; support rails for hanging slats which support rails are disposed within the slat stowing box; a plurality of slats each provided on both sides of the upper end thereof with slat hanging rollers which are movable along the support rails and the vertical guide rails, the slats being connected to a pair of right and left chains each through the slat hanging rollers; and drive means for vertically moving each slat between the vertical guide rails through sprockets engaged with the chains and also moving each slat into the slat stowing box.
The vertical slat drive means is mounted rotatably within the slat stowing box and it has a long rotative shaft engaged with the paired chains and rotated by means of, for example, a geared motor.
Upon operation of the vertical slat drive means in one direction, its rotational force is transmitted to the rotative shift of the drive means and the sprockets are driven rotatively, whereby the slats in the slat stowing box are pulled out successively to the opening between the vertical guide rails through the chains and go down. In this way the slats are arranged in the form of a single vertical plane to close the opening between the vertical guide rails. On the other hand, upon operation of the vertical slat drive means in the opposite direction, the slats arranged between the vertical guide rails go up successively into the slat stowing box, in which the slat hanging rollers mounted on both sides of the upper end of each slat come into engagement with the upper surfaces of the support rails, whereby the slats are suspended in a parallel, folded condition.
More specifically, the vertical slat drive means has a first rotative shaft which is driven by means of, for example, a geared motor and a second rotative shaft for moving the slats up and down interlockedly with the first rotative shaft. On the first rotative shaft are mounted a second sprocket interlocked through an endless chain with a first sprocket which is integral with an output shaft of the geared motor, a pair of right and left, output-side, third and fourth sprockets for driving both the right and left chains, and a fifth sprocket on the output side for transferring the rotational force to the second rotative shaft, while on the second rotative shaft are mounted a sixth sprocket for inputting the rotational force from the first rotative shaft through the fifth sprocket and an endless chain, and a pair of right and left, seventh and eighth sprockets for winding and engaging the chains with respect to the third and fourth sprockets.
When the first rotative shaft is rotated in one direction by the vertical slat drive means, its rotational force is transmitted to the second rotative shaft, whereby the slats stowed in the top box are pulled out to the opening between the vertical guide rails through the chains and go down. In this way the slats are arranged in the form of a single vertical plane to close the opening between the vertical guide rails. On the other hand, when the second rotative shaft is rotated in the opposite direction through the first rotative shaft by the vertical slat drive means, the slats arranged between the vertical guide rails go up successively into the top box, in which the slat hanging rollers positioned on both sides of the upper end of each slat comes into engagement with the upper surfaces of the support rails, whereby the slats are suspended in a parallel, folded condition.
The support rails are each formed by bending a metallic plate in the channel shape in section, and the shaft portion of the slat hanging roller is brought into rolling engagement with the upper end of the vertical wall portion on one side of the channel.
Consequently, the concentric roller portion of a larger diameter connected integrally with the above roller shaft portion floats from the support rail and it functions as a rotation stopping flange portion to prevent the roller shaft portion from being disengaged from the upper surface of the support rail.
In the slat opening/closing drive mechanism of the above conventional shutter equipment, however, the chains are engaged with the sprockets inside the bent portions extending from the vertical guide rails in the slat stowing direction within the top box and as many as eight sprockets in all are used, so if the sprockets are disposed in proximity to the upper corner portions in the box, the chains engaged with the sprockets become too close to the inner wall of the box, resulting in interference of the chains and slats with the inner wall, and thus there occur inconveniences in the shutter opening and closing operation.
Therefore, the sprockets cannot be disposed in proximity to the upper corner portions in the top box or the slat stowing box, resulting in that a dead space is formed in the box. So the internal space cannot be utilized effectively and the entire equipment becomes larger in size, causing increase of the cost.
In the slat opening/closing drive mechanism of the above conventional shutter equipment, moreover, since the rotative shaft is supported only at both end portions thereof despite of it being a long shaft, the rotative shaft deflects and a slat moving in the slat stowing box interferes with the rotative shaft, whereby the rotation of the rotative shaft is prevented, so that the slats can no longer be operated smoothly for its opening or closing motion.
Further, in the above conventional shutter equipment, only both side portions of the upper end of each slat are supported on the support rails in a suspended state through the slat hanging rollers and the lower portion of the slat is free. As the slat hanging rollers roll on the support rails in this state, the slats move in a vertical posture, so if the slats are moved at high speed, the will be deflected largely due to wind pressure.
Such deflections cause the slats to interfere with each other, giving rise to a loud noise and flaw of the slats, thus requiring decrease of the slat moving speed.
In such conventional shutter slat hanging and supporting mechanism, the shaft portion of each slat hanging roller is supported in linear contact with the upper end of the vertical wall portion on one side of the support rail and the thickness of the said vertical wall portion corresponds to only the thickness of the metallic plate, that is, it is very thin, so that a considerable load including the weight of each slat acts concentratively on the vertical wall portion. Consequently, both the vertical wall portion and the roller shaft portion wear out in an early stage, thus resulting in loss of durability.
Further, the slat hanging rollers and the support rails must be formed of a metal to ensure strength sufficient to withstand the above concentrated load, thus leading to increase of the cost inevitably and causing a loud metallic noise during rolling of the rollers.
In the above conventional shutter slat support structure, pins for connection to chains are integrally projected from both sides of the upper portion of each slat and are inserted into partially bent portions of the chains through hollow pins rotatably and movably in the thrust direction. Therefore, it is impossible to make large the diameter of such chain connection pins and for this reason, although there is no problem in point of pin strength if the weight per slat is light, a heavy weight per slat inevitably requires increase in diameter of each pin to enhance the pin strength. In this case, it has been impossible to cope with this problem in point of pin strength unless the size of each chain itself is made larger.
When there occurs an error within an allowable range in the spacing between a pair of right and left guide rails to which are secured each slat through chains and rollers as mentioned above, each chain connection pin is moved in the thrust direction of the hollow pin of the chain to absorb and correct the error, but its moving stroke is restricted by the length of the hollow pin because the chain connection pin is inserted into the hollow pin extending through the chain link pin and the roller portion projecting from the chain, so when the above error is large, it is necessary to make the hollow pin longer to absorb and correct the error exactly by moving the pin.
However, making the hollow pin longer results in increase in the distance from the projecting roller up to the slat end portion from which the chain connection pin is projecting integrally, and this result is contrary to the market demand for a more compact structure.